The P2X7 receptor is a ligand-gated ion channel that belongs to the Purinergic Receptor Family. The receptor is expressed on many cell types related to the immune and nervous systems. In the nervous system P2X7 is expressed on microglia, oligodendrocytes and astrocytes. Brief activation of the P2X7 receptor channel with its endogenous ligand ATP leads to several downstream events including the processing and release of the proinflammatory cytokine IL1-β from monocytes and macrophages. P2X7 activation also plays an important role in regulating the glutamate release/uptake in astrocytes.
P2X7 receptors are ionotropic receptors activated by ATP, which may regulate neurotransmission in the CNS by activating presynaptic and/or postsynaptic P2X7 receptors on central and peripheral neurons and glia (Deuchars S. A. et al., J. Neurosci. 21:7143-7152, (2001), Kanjhan R. et al., J. Comp. Neurol. 407:11-32 (1997), Le K. T. et al., Neuroscience 83:177-190 (1998)). Activation of the P2X7 receptor on cells of the immune system (macrophages, mast cells and lymphocytes) leads to release of interleukin-1β (IL-1β), giant cell formation, degranulation, and L-selectin shedding. ATP is able to increase local release and process of IL-1 in rats through a P2X7 receptor mediated mechanism following lipopolysaccharide (LPS) intraperitoneal injections (Griffiths et al., J. Immunology Vol. 154, pages 2821-2828 (1995); Solle et al., J. Biol. Chemistry, Vol. 276, pages 125-132, (2001)).
Antagonism of the P2X7 receptor is considered to be an attractive therapeutic approach for the treatment of multiple sclerosis and Alzheimer's disease, due to its significant role in dampening the CNS inflammation and supporting neuroprotection.